The present invention is direction to a sheet conveying device for a copying machine and more specifically to the configuration of the chute for guiding a sheet from the image transfer station to a fixing station.
In conventional copying machines, such as that shown in FIG. 1, a supply tray 1 holds a supply of sheets which are fed into the machine one at a time by means of a sheet feeding roll 2. A photo-sensitive drum 4 is provided for transferring a toner image onto the copy sheet in the transfer section 3 in the conventional well known manner. The feed direction of the copy sheet is then changed by passage around the roll 5 between the roll 5 and a pinch roll 6. The sheet is then forwarded along the chute 9 to the fixing section which includes a heating roll 7 and a pressure roll 8. The sheet is then discharged from the copying machine by means of discharge roll 10.
The chute 9 is provided with a substantially flat conveying surface for the copy sheet with the discharge end 9a thereof being aligned with the nip region between the heating roll 7 and the pressure roll 8 for smoothly guiding the copy sheet between the rolls 7 and 8 without creasing the sheet. A heat shield plate 8 is located adjacent the heating roll 7 and is disposed in close proximity to the discharge end 9a of the chute 9. After the trailing edge of a sheet moving on the chute 9 moves out of engagement with the rolls 5 and 6, the sole feeding means for the sheet are the rolls 7 and 8. Thus, there is a tendency for the trailing end of the copying sheet to be lifted from the surface of the chute 9 so as to be brought into contact with the heat shield plate 11 which frequently results in the smudging of the toner on the copy sheet. While the roll 8 has a uniform cylindrical surface, the roll 7 increases in diameter from the center towards both ends thereof. Accordingly, the central portion of the sheet tends to be lifted to cause a floating action of the trailing edge of the sheet off the surface of the chute 9.